McClain, Robert L.

Abstract Introduction: Total knee arthroplasty (TKA) for knee osteoarthritis (OA) provides pain relief and functional improvement for many patients. The endocannabinoid system (ECS) regulates pain and inflammation through central and peripheral mechanisms and may be affected by acetaminophen. There is limited information on how surgery and perioperative care affect the ECS. Objective: We designed this study to examine the effect of surgery and acetaminophen on the ECS and determine whether perioperative endocannabinoids were associated with pain resolution after surgery. Methods: Forty adult patients with OA undergoing TKA were enrolled in a prospective observational cohort study and provided preoperative cerebrospinal fluid (CSF) and blood samples at 3 time points (before surgery, after intravenous acetaminophen, and 24 hours postoperative). Defense and Veterans Pain Rating Scale scores at rest and with activity were recorded in the preoperative holding area, in the operating room after intravenous acetaminophen before spinal anesthesia, and 24 to 48 hours postoperatively. Cerebrospinal fluid and plasma endocannabinoids were quantified using a validated liquid chromatography/mass spectrometry assay. We analyzed the data using linear regression models with sex, age, and body mass index as covariates. Results: Patients undergoing TKA have higher CSF and plasma concentrations of N-acylethanolamines anandamide and its congeners compared with control subjects. Patients with higher pain scores had lower CSF anandamide levels before and after surgery and higher levels of 2-arachidonoylglycerol before surgery but not after. Conclusion: Chronic pain, acetaminophen, and surgery are associated with endogenous endocannabinoid levels and may present an opportunity for developing targeted nonopioid perioperative analgesia after TKA.

AbstractIntroductionRadiologically inserted gastrostomy (RIG) placement in patients with amyotrophic lateral sclerosis (ALS) carries risks related to periprocedural sedation and analgesia. To minimize these risks, we used a paravertebral block (PVB) technique for RIG placement.MethodsWe retrospectively reviewed patients with ALS undergoing RIG placement under PVB between 2013 and 2017.ResultsNinety‐nine patients with ALS underwent RIG placement under PVB. Median (range) age was 66 (28 to 86) years, ALS Functional Rating Scale—Revised score was 27 (6 to 45), and forced vital capacity was 47% (8%–79%) at time of RIG placement. Eighty‐five (85.9%) patients underwent RIG placement as outpatients, with a mean postanesthesia care unit stay of 2.3 hours. The readmission rate was 4% at both 1 and 30 days postprocedure.DiscussionPVB for RIG placement has a low rate of adverse events and provides effective periprocedural analgesia in patients with ALS, the majority of whom can be treated as outpatients.

The field of abdominal organ transplantation is multifaceted, with the clinician balancing recipient comorbidities, risks of the surgical procedure, and the pathophysiology of immunosuppression to ensure optimal outcomes. An underappreciated element throughout this process is acute pain management related to the surgical procedure. As the opioid epidemic continues to grow with increasing numbers of transplant candidates on opioids as well the increase in the development of enhanced recovery after surgery protocols, there is a need for greater focus on optimal postoperative pain control to minimize opioid use and improve outcomes. This review will summarize the physiology of acute pain in transplant recipients, assess the impact of opioid use on post-transplant outcomes, present evidence supporting nonopioid analgesia in transplant surgery, and briefly address the perioperative approach to the pretransplant recipient on opioids.